In conventional circuits, a switch can be operated to connect a first circuit section to a second circuit section. If, for instance, the first circuit section has a current source, this can be connected to the second circuit section when required by operating the switch. The bipolar transistor used as switching element of the switch is usually operated in the forward direction. When the bipolar transistor is operated in inverse mode (in the reverse direction), it switches reliably only as long as its collector-emitter voltage does not exceed the collector-emitter breakdown voltage. As soon as its collector-emitter voltage exceeds this value, the bipolar transistor breaks down with the result that a considerable leakage current can be supplied via the bipolar transistor to the first circuit section where it creates undesirable temporary or even permanent functional disturbances.